【作者】 肖培培；

【导师】 钱逸泰；

【作者基本信息】 中国科学技术大学 ， 无机化学， 2011， 博士

【摘要】 本论文探索了水热合成、室温水相化学合成以及混合溶剂热合成制备了BiOBr,Bi₂O₃,CoTe₂和PbSe纳米材料。水热条件下制备了微米花状BiOBr和凹面梭子状的Bi₂O₃,在前面的工作基础上,我们还进一步在室温下采用水相合成方法合成了直径约为500 nm的亚微米花状BiOBr纳米结构。采用水和二乙烯三胺（DETA）的混合溶剂合成了骰子状立方块PbSe晶体;用水、三乙烯四胺（TETA）和水合肼的混合溶剂,添加表面活性剂CTAB合成了由纳米棒组成的花状CoTe₂纳米结构。主要内容归纳如下:1.通过调节NaOH的加入量,在Bi（NO₃）₃–十六烷基三甲基溴化铵（CTAB）–NaOH反应体系中通过水热法合成不同形貌的BiOBr和Bi₂O₃。在酸性条件下,合成了微米花状的BiOBr,该微米花是由厚度为20 nm的单晶纳米片组成的;在较强的碱性条件下,合成了Bi₂O₃凹面梭子状形貌,梭子的长约100μm,中间宽度微为50 ?μm。通过在可见光下降解甲基橙水溶液来检测微米花状BiOBr的光催化活性,其降解效率在90 min内达到了96%。在前面的工作基础上,在室温下,以Bi（NO₃）₃和四乙基溴化胺（TEAB）作为反应原料,通过简单的液相反应合成了大量的BiOBr亚微米花状纳米结构,其直径约为500 nm,结构观察表明这些亚微米花状结构是由厚为20 nm的BiOBr单晶纳米片组成的。合成的亚微米花状BiOBr能分别在可见光和紫外线照射下降解甲基橙和苯酚水溶液,降解效率分别达到了在1.5 h达到97%和4 h达到45%。2.在二乙烯三胺的存在下,以Na₂SeO₃为Se源,通过混合溶剂法合成PbSe骰子状立方块晶体,立方块晶体的边长在1.5μm到2.5μm之间。DETA在反应中起到了还原剂和溶剂的作用。3.通过三乙烯四胺和CTAB的协同作用,大规模地合成出了花状CoTe₂纳米结构。这些花状结构是由直径约为50 nm的纳米棒组成的。实验结果表明三乙烯四胺和CTAB在反应中作为主要的络合剂和capping试剂影响着CoTe₂晶体的生长,在控制产物的形貌和相成分方面都起到了关键作用。更多还原

【Abstract】 The aim of this dissenation is to explore the synthesis of BiOBr, Bi₂O₃,PbSe,and CoTe₂ nanomaterials by hydrothermal method, room temperature chemical solution route and mixed-solvothemal technique. BiOBr microflowers and Bi₂O₃ shuttles with concave surfaces have been synthesized through a hydrothermal method; Based on the previous work, BiOBr sub-microflowers with the diameter of 500 nm have been prepared at room temperature. Well-crystalline PbSe cuboidal structures with different concave faces in each plane have been prepared through a solvothermal process using diethylenetriamine （DETA） and distilled water as mixed solvent. Flower-like CoTe₂ nanostructures have been synthesized on a large scale using triethylenetetramine （TETA）,N2H4·H2O and distilled water as mixed solvent with adding hexadecyl trimethyl ammonium bromide （CTAB）. The main contents can be summarized as follows:1. Through controlling the amount of NaOH added, BiOBr and Bi₂O₃ with different shapes were hydrothermally synthesized in the reaction system of Bi（NO₃）₃–hexadecyl trimethyl ammonium bromide （CTAB）–NaOH. In acid condition, BiOBr microflowers constructed of nanoflakes were synthesized. The thickness of these single-crystal nanoflakes was about twenty nanometers. In more basic condition, Bi₂O₃ shuttles with concave surfaces were obtained. The length of these shuttles was 100μm and the diameter at the middle of these shuttles was 50μm. The photocatalytic activity of as-prepared BiOBr microflowers was evaluated by the degradation of methyl orange （MO） under visible-light irradiation （λ> 420 nm）, which was up to 96% within 90 min. Based on the previous work, flower-like BiOBr sub-microstructures about 500 nm in diameter have been synthesized in the presence of Bi（NO₃）₃ and tetraethylammonium bromide （TEAB） by a solution route at room temperature. These sub-microflowers are composed of nanoflakes with the thickness of 20 nm. The photocatalytic activities of flower-like BiOBr were evaluated by the degradation of methyl orange （MO） and phenol under visible-light and UV-light irradiation, with the efficiencies up to 97% within 1.5 h and 45% within 4 h, respectively.2. A facile mixed-solvothermal method for the preparation of the cuboidal structures with different concave faces in each plane has been established using Na₂SeO₃ as selenium source. The FESEM showed that the edge lengths of these cuboidal crystals ranged from 1.5 to 2.5μm, and the edges of a cube crystal extend outwards from its core with a tiny cubic center leaving step-like faces. DETA acts both as the reducer and the solvent.3. Well-crystallined flower-like CoTe₂ nanostructures have been synthesized on a large scale by a triethylenetetramine （TETA） and hexadecyl trimethyl ammonium bromide （CTAB） synergistic-assisted solvothermal route. The TEM results showed that the product was flower-like nanostructures composed of packed nanorods with an average diameter of 50 nm. The influence factors of synthesizing flower-like CoTe₂ nanostructures such as the volume ratio of mixed solvent and the amount of CTAB were discussed, which indicated that both TETA and CTAB played crucial roles in controlling phase composition and morphology of the resultant products.更多还原